1. Field of the Invention
The present invention relates to a method of forming a low-resistance metal pattern, a patterned metal structure and display devices using the same, and, more particularly, to a method of forming low-resistance metal pattern, which can be used to obtain metal pattern having stable and excellent characteristics by performing sensitization treatment using a copper compound before activation treatment to form uniform and dense metal cores, a patterned metal structure, and display devices using the same.
2. Description of the Related Art
As electronic devices gradually become miniaturized and increasingly integrated, the pattern width decreases so that the resistance of metal pattern increases, which causes signal delayed, thereby deteriorating the display quality of the electronic devices. Accordingly, the problems can become significant obstacles to the development of TFT-LCDs having high image quality and large areas. In order to realize high-speed and highly integrated electronic devices and products, copper (Cu), which has lower electric resistance and higher charge mobility than conventional aluminum, molybdenum and chromium, and thus is able to overcome the delay of driving signals (RC delay), is useful as a pattern material to produce such devices and products. Copper has low specific resistance and excellent electromigration resistance. Attempts to develop various novel technologies that take advantage of the characteristics of copper are continuously being made.
In electronic devices, such as integrated circuits (“IC”), liquid crystal display devices (“LCD”), and the like, metal patterns, which are formed on a substrate, are gradually being miniaturized to accommodate the increase in the degree of integration required in such devices from the miniaturization of these devices. To form metal micropatterns on a substrate by a conventional method, a metal pattern is formed by sputtering the entire surface of a substrate with metal, forming a pattern thereon by a photolithography process using a photoresist, and then etching the exposed metal to form a metal pattern, and removing the photoresist.
Since these conventional methods of forming a metal pattern need expensive equipment and use methods such as a sputtering method which must be performed at a high temperature, the number of such processing steps that are required and the investment cost for manufacturing the necessary equipment are each high, which increases the overall manufacturing cost.
However, among the methods of forming copper pattern, an electroless plating method which plates a metal film by the reaction of a reductant and an oxidant in solution to provide the metal at the surface of an activated substrate. Advantageously, since the electroless plating method is simultaneously performed over the entire substrate, the manufacturing cost is low, processes are simple, and productivity is high.
In the electroless plating method, since a metal film is directly plated on a diffusion-preventing film using an electrochemical method, any microstructures located at the interface between the diffusion preventing film and the metal film, reactions occurring on the interface, and the like, have an influence on all of the characteristics of the metal pattern provided thereby, including electrical properties, thermal stability, and the like. Further, in an exemplary electroless plating method, catalyst metal cores are formed on a lower conductive pattern film by activating the lower conductive pattern film before the formation of the plated metal layer. Since the catalyst metal cores catalyze the plating process, the plating process can thus be readily performed. Accordingly, a technology for forming uniform and dense catalyst metal cores in an activation process is an important aspect of the technology for forming a stable plated layer having desirable qualities through the electroless plating process.
To perform an activation process when the electroless plating is conducted on an insulating film, methods of performing sensitization treatment using SnCl2 are known. These methods are performed for the purpose of increasing the uniformity and density of metal cores formed by the activation process.
However, a plated film formed by activation treatment performed using tin and palladium has insufficient adhesion to the substrate, and thus it is unsuitable for practical use.